CELP speech coder using novel LPC interpolation and fast codebook search method

An LPC (linear predictive coder) interpolation technique is presented which is based on interpolating the impulse response of the LPC synthesis filter. After reviewing the basic concept of the CELP (code-excited linear predictive) speech coder, the complexity associated with the excitation codebook search is discussed. The author then describes the method of interpolating the impulse response of the LPC synthesis filter. The fast codebook search algorithm for the CELP coder based on the new interpolation method is described, and experimental results with this coder are presented. It is noted that this method offers a significant complexity reduction for the codebook search over other typical interpolation schemes. Furthermore, it outperforms other interpolation methods at low bit-rates